Originally Posted by mhnadel

The key question on this is whether you will have any checked luggage.

United has its own immigration and customs area at LAX and my experience is that it's one of the quickest in the U.S.. (But I am a U.S. citizen, so my experience may not be typical.) I've usually gotten through there in under 10 minutes.

T6 and T7 are physically connected and a very short walk.

So the problem is the potential wait for a checked bag to show up.

I'd probably book the later flight to LAS and try to get standby on the earlier one if I made it through quickly.